Serum substance P concentrations to predict oocyte maturation index and clinical pregnancy

The aim of this study was to assess the predictive value of serum substance P (SP) concentrations on oocyte maturation and clinical pregnancy.

Ninety-three women with unexplained infertility underwent intracytoplasmic sperm injection (ICSI) cycles. Antagonist protocol was started for each participant and at the day of oocyte pick up, serum samples were obtained from each participant to assess SP concentrations, and these concentrations were utilized to predict mature/total oocyte ratio and clinical pregnancy.

SP concentration was a significant predictor for mature/total oocyte ratio > 0.75 and clinical pregnancy. In correlation analyses, maturation index was significantly correlated with FSH (r= -0.226, p = 0.03), estradiol (r = 0.239, p = 0.021), peak estradiol (r = 0.414, p < 0.001), and substance P (r = 0.796, p < 0.001). In multivariate analyses, number of immature (beta coefficient = -0.379, p < 0.001), mature oocyte (beta coefficient = 0.473, p < 0.001), SP concentration (beta coefficient = 0.723, p < 0.001) and maturation index (beta coefficient = -0.387, p = 0.003) were significantly associated with clinical pregnancy.

SP concentrations at the day of oocyte pick up may be used to predict clinical pregnancy and may be an indirect indicator for cycle outcome in assisted reproductive technology (ART).